这个简单、 (5xy-2y²)-(-x²+3xy-y²)
=5xy-2y²+x²-3xy+y²
=2xy-y²+x²
( 2xy-y²+x²)-(-x²+3xy-y²)
=2xy-y²+x²+x²-3xy+y²
=-xy+2x²
答:正确答案为 -xy+2x².
这个简单、 (5xy-2y²)-(-x²+3xy-y²)
=5xy-2y²+x²-3xy+y²
=2xy-y²+x²
( 2xy-y²+x²)-(-x²+3xy-y²)
=2xy-y²+x²+x²-3xy+y²
=-xy+2x²
答:正确答案为 -xy+2x².